Get hostname from $fqdn variable rather than from $hostname

Using $hostname at this site results in a csync2 configuration file
containing only the short hostname, and csync2 fails to accept the group.
Giving it $fqdn makes it all work.
Manage csync2 confdir

The run has a habit of erroring out if it tries to write to the confdir
before the csync2 package is installed. We hereby start managing the
directory directly and add ordering dependencies on it.